package com.why.encrption;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.text.TextUtils;
import android.util.Base64;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;

import java.security.Key;
import java.security.NoSuchAlgorithmException;

import javax.crypto.Cipher;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.SecretKeySpec;

public class MainActivity extends AppCompatActivity {

    //输入加密的内容和密码
    private EditText input,pw;
    //显示操作后的内容
    private TextView showInfo;
    private String encryptResult = null;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        initView();
    }

    private void initView() {
        input = (EditText) findViewById(R.id.input);
        pw = (EditText) findViewById(R.id.pw);
        showInfo = (TextView) findViewById(R.id.showInfo);
    }

    //加密解密的点击事件
    public void encrypt(View view) {

        String data = input.getText().toString().trim();
        String pw = this.pw.getText().toString().trim();
        String decryptResult = null;
        switch (view.getId()){
            case R.id.desEncrypt://des加密
                //需要类型，要加密的内容，需要密码
                encryptResult = encrypt("DES", data, pw);
                showInfo.setText("DES加密的内容是："+data+",加密的结果是："+encryptResult);
                break;
            case R.id.desDecrypt://des解密
                decryptResult = decrypt("DES", encryptResult, pw);
                showInfo.setText("DES解密结果是："+decryptResult);
                break;
            case R.id.desedeEncrypt:
                encryptResult = encrypt("DESede", data, pw);
                showInfo.setText("3DES加密的内容是："+data+",加密的结果是："+encryptResult);
                break;
            case R.id.desedeDecrypt:
                decryptResult = decrypt("DESede", encryptResult, pw);
                showInfo.setText("3DES解密结果是："+decryptResult);
                break;
            case R.id.aesEncrypt://美国军方加密的工具，美国地龙系统
                encryptResult = decrypt("AES", data, pw);
                showInfo.setText("AES加密的内容是："+data+",加密的结果是："+encryptResult);
                break;
            case R.id.aesDecrypt:
                decryptResult = decrypt("AES", encryptResult, pw);
                showInfo.setText("AES解密结果是："+decryptResult);
                break;
        }

    }

    private String decrypt(String type, String data, String pw) {

        switch (type){
            case "DES":
                //1.获取解密所对应的类
                try {
                    Cipher cipher = Cipher.getInstance(type);

                    //2.对解密引擎进行初始化，制定加密的密码
                    if (pw.getBytes().length!=8){
                        throw new Exception("密码长度必须时8位");
                    }
                    Key key = new SecretKeySpec(pw.getBytes(), type);

                    cipher.init(Cipher.DECRYPT_MODE, key);

                    //3.执行解密
                    if (!TextUtils.isEmpty(data)) {
                        //Base64逆运算，加密时，为了内容不乱码，进行了Base64编码
                        //解密的内容，就是经过Base编码
                        byte[] base64Decode = Base64.decode(data.getBytes(), Base64.DEFAULT);
                        byte[] decryptBytes = cipher.doFinal(base64Decode);
                        return new String(decryptBytes);
                    }

                } catch (NoSuchAlgorithmException e) {
                    e.printStackTrace();
                } catch (NoSuchPaddingException e) {
                    e.printStackTrace();
                } catch (Exception e) {
                    e.printStackTrace();
                }

                break;
            case "DESede":
                //1.获取解密所对应的类
                try {
                    Cipher cipher = Cipher.getInstance(type);

                    //2.对解密引擎进行初始化，制定加密的密码
                    if (pw.getBytes().length!=24){
                        throw new Exception("密码长度必须时24位");
                    }
                    Key key = new SecretKeySpec(pw.getBytes(), type);

                    cipher.init(Cipher.DECRYPT_MODE, key);

                    //3.执行解密
                    if (!TextUtils.isEmpty(data)) {
                        //Base64逆运算，加密时，为了内容不乱码，进行了Base64编码
                        //解密的内容，就是经过Base编码
                        byte[] base64Decode = Base64.decode(data.getBytes(), Base64.DEFAULT);
                        byte[] decryptBytes = cipher.doFinal(base64Decode);
                        return new String(decryptBytes);
                    }

                } catch (NoSuchAlgorithmException e) {
                    e.printStackTrace();
                } catch (NoSuchPaddingException e) {
                    e.printStackTrace();
                } catch (Exception e) {
                    e.printStackTrace();
                }
                break;
            case "ASE":
                //1.获取解密所对应的类
                try {
                    Cipher cipher = Cipher.getInstance(type);

                    //2.对解密引擎进行初始化，制定加密的密码
                    if (pw.getBytes().length!=16){
                        throw new Exception("密码长度必须时16位");
                    }
                    Key key = new SecretKeySpec(pw.getBytes(), type);

                    cipher.init(Cipher.DECRYPT_MODE, key);

                    //3.执行解密
                    if (!TextUtils.isEmpty(data)) {
                        //Base64逆运算，加密时，为了内容不乱码，进行了Base64编码
                        //解密的内容，就是经过Base编码
                        byte[] base64Decode = Base64.decode(data.getBytes(), Base64.DEFAULT);
                        byte[] decryptBytes = cipher.doFinal(base64Decode);
                        return new String(decryptBytes);
                    }

                } catch (NoSuchAlgorithmException e) {
                    e.printStackTrace();
                } catch (NoSuchPaddingException e) {
                    e.printStackTrace();
                } catch (Exception e) {
                    e.printStackTrace();
                }
                break;
            default:
                try {
                    throw new Exception("解密的类型不匹配，请选择以下几种解密方式：DES,DESede,ASE");
                } catch (Exception e) {
                    e.printStackTrace();
                }
                break;
        }

        return null;

    }

    private String encrypt(String type, String data, String pw) {

        switch (type){
            case "DES":
                //1.获取加密所对应的类
                try {
                    Cipher cipher = Cipher.getInstance(type);

                    //2.对加密引擎进行初始化，制定加密的密码
                    if (pw.getBytes().length!=8){
                        throw new Exception("密码长度必须时8位");
                    }
                    Key key = new SecretKeySpec(pw.getBytes(), type);

                    cipher.init(Cipher.ENCRYPT_MODE, key);

                    //3.执行加密
                    if (!TextUtils.isEmpty(data)) {
                        byte[] encryptBytes = cipher.doFinal(data.getBytes());

                        byte[] base64Encode = Base64.encode(encryptBytes, Base64.DEFAULT);

                        return new String(base64Encode);
                    }

                } catch (NoSuchAlgorithmException e) {
                    e.printStackTrace();
                } catch (NoSuchPaddingException e) {
                    e.printStackTrace();
                } catch (Exception e) {
                    e.printStackTrace();
                }

                break;
            case "DESede":
                //1.获取加密所对应的类
                try {
                    Cipher cipher = Cipher.getInstance(type);

                    //2.对加密引擎进行初始化，制定加密的密码
                    if (pw.getBytes().length!=24){
                        throw new Exception("密码长度必须时24位");
                    }
                    Key key = new SecretKeySpec(pw.getBytes(), type);

                    cipher.init(Cipher.ENCRYPT_MODE, key);

                    //3.执行加密
                    if (!TextUtils.isEmpty(data)) {
                        byte[] encryptBytes = cipher.doFinal(data.getBytes());

                        byte[] base64Encode = Base64.encode(encryptBytes, Base64.DEFAULT);

                        return new String(base64Encode);
                    }

                } catch (NoSuchAlgorithmException e) {
                    e.printStackTrace();
                } catch (NoSuchPaddingException e) {
                    e.printStackTrace();
                } catch (Exception e) {
                    e.printStackTrace();
                }
                break;
            case "ASE":
                //1.获取加密所对应的类
                try {
                    Cipher cipher = Cipher.getInstance(type);

                    //2.对加密引擎进行初始化，制定加密的密码
                    if (pw.getBytes().length!=16){
                        throw new Exception("密码长度必须时16位");
                    }
                    Key key = new SecretKeySpec(pw.getBytes(), type);

                    cipher.init(Cipher.ENCRYPT_MODE, key);

                    //3.执行加密
                    if (!TextUtils.isEmpty(data)) {
                        byte[] encryptBytes = cipher.doFinal(data.getBytes());

                        byte[] base64Encode = Base64.encode(encryptBytes, Base64.DEFAULT);

                        return new String(base64Encode);
                    }

                } catch (NoSuchAlgorithmException e) {
                    e.printStackTrace();
                } catch (NoSuchPaddingException e) {
                    e.printStackTrace();
                } catch (Exception e) {
                    e.printStackTrace();
                }
                break;
            default:
                try {
                    throw new Exception("加密的类型不匹配，请选择以下几种加密方式：DES,DESede,ASE");
                } catch (Exception e) {
                    e.printStackTrace();
                }
                break;
        }


        return null;
    }
}
